Objective: This study focuses on cooperation between physicians and managers and aspects of that cooperation that can provide leads for interventions aimed at enhancing hospital performance. - Design: We performed a qualitative study on cooperation between physicians and managers and the influence of that cooperation on hospital performance, and structured the resulting data according to the conditions of Allport's theory on intergroup conflicts. - Setting: General hospitals in the Netherlands. - Participants: Thirty physicians (surgical and internal) and managers (strategic, tactic and operational) working in five different hospitals. - Interventions: In-depth interviews exploring the influence of cooperation between physicians and managers on hospital performance. - Main Outcome Measures: Respondents confirmed the complexity of the relationship between physicians and managers and the link between their cooperation and hospital performance. Mentioned aspects such as power and status differences, clarity in decision-making and personal click, are important in determining the effectiveness of the cooperation between physicians and managers. - Results: Our study suggests that the effectiveness of cooperation between physicians and managers is related to the uptake of quality initiatives and hospital performance. - Conclusions: The complex relationship between physicians and managers can be referred to as an intergroup conflict situation. We combined Allport's Contact theory conditions with aspects found in our study leading to the following facilitating conditions: address common goals; create interdependent tasks; arrange the support of authorities and respect the medical domain. They will enhance intra-hospital cooperation and therewith hospital performance.